Method for controlling telemetry in an implantable medical device based on power source capacity

ABSTRACT

An implantable microstimulator configured for implantation beneath a patient&#39;s skin for tissue stimulation to prevent and/or treat various disorders, uses a self-contained power source. Periodic or occasional replenishment of the power source is accomplished, for example, by inductive coupling with an external device. A bidirectional telemetry link allows the microstimulator to provide information regarding the system&#39;s status, including the power source&#39;s charge level, and stimulation parameter states. Processing circuitry automatically controls the applied stimulation pulses to match a set of programmed stimulation parameters established for a particular patient. The microstimulator preferably has a cylindrical hermetically sealed case having a length no greater than about 27 mm and a diameter no greater than about 3.3 mm. A reference electrode is located on one end of the case and an active electrode is located on the other end. The case is externally coated on selected areas with conductive and non-conductive materials.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/038,131 now U.S. Pat. No. 8,914,129, filed Sep. 26, 2013, which is adivisional of U.S. patent application Ser. No. 13/218,636 (now U.S. Pat.No. 8,571,679), filed Aug. 26, 2011, which is a continuation of U.S.patent application Ser. No. 12/533,697, filed Jul. 31, 2009 (now U.S.Pat. No. 8,032,227), which is a divisional of U.S. patent applicationSer. No. 11/534,548, filed Sep. 22, 2006 (now U.S. Pat. No. 7,587,241),which is a divisional of U.S. patent application Ser. No. 10/607,963,filed Jun. 27, 2003 (now U.S. Pat. No. 7,437,193), which in turn claimsthe benefit of U.S. Provisional Patent Application Ser. No. 60/392,475,filed Jun. 28, 2002. Priority is claimed to all of these applications,and all are incorporated herein by reference in their entireties.

TECHNICAL FIELD

The present invention relates generally to the field of implantablemedical devices and more particularly to microstimulator devicesincorporating a self-contained power source, such as a primary batteryor a rechargeable battery, for powering the internal electroniccircuitry.

BACKGROUND ART

Implantable microstimulators, also known as BION® devices (where BION®is a registered trademark of Advanced Bionics Corporation, of Sylmar,Calif.), are typically characterized by a small, cylindrical housingwhich contains electronic circuitry that produces electric currentsbetween spaced electrodes. These microstimulators are implantedproximate to target tissue, and the currents produced by the electrodesstimulate the tissue to reduce symptoms or otherwise provide therapy forvarious disorders. An implantable battery-powered medical device may beused to provide therapy for various purposes including nerve or musclestimulation. For example, urinary urge incontinence may be treated bystimulating the nerve fibers proximal to the pudendal nerves of thepelvic floor; erectile or other sexual dysfunctions may be treated byproviding stimulation of the cavernous nerve(s); and other disorders,e.g., neurological disorders caused by injury or stroke, may be treatedby providing stimulation of other appropriate nerve(s).

Implantable microstimulators have been disclosed that provide therapyfor neurological disorders by stimulating the surrounding nerves ormuscles. Such devices are characterized by a sealed housing thatcontains electronic circuitry for producing electric currents betweenspaced electrodes. A microstimulator is precisely implanted proximate tothe target tissue area and the electrical currents produced at theelectrodes stimulate the tissue to reduce the symptoms and otherwiseprovide therapy for the neurological disorder.

A battery-powered microstimulator of the present invention is preferablyof the type referred to as a BION® device, which may operateindependently, or in a coordinated manner with other implanted devices,or with external devices.

By way of example, in U.S. Pat. No. 5,312,439, entitled ImplantableDevice Having an Electrolytic Storage Electrode, an implantable devicefor tissue stimulation is described. U.S. Pat. No. 5,312,439 isincorporated herein by reference. The described microstimulator shown inthe '439 patent relates to an implantable device using one or moreexposed, electrolytic electrodes to store electrical energy received bythe implanted device, for the purpose of providing electrical energy toat least a portion of the internal electrical circuitry of theimplantable device. It uses an electrolytic capacitor electrode to storeelectrical energy in the electrode when exposed to body fluids.

Another microstimulator known in the art is described in U.S. Pat. No.5,193,539, “Implantable Microstimulator,” which patent is alsoincorporated herein by reference. The '539 patent describes amicrostimulator in which power and information for operating themicrostimulator is received through a modulated, alternating magneticfield in which a coil is adapted to function as the secondary winding ofa transformer. The induction coil receives energy from outside the bodyand a capacitor is used to store electrical energy, which is released tothe microstimulator's exposed electrodes under the control of electroniccontrol circuitry.

In U.S. Pat. Nos. 5,193,540 and 5,405,367, which patents areincorporated herein by reference, a structure and method of manufactureof an implantable microstimulator is disclosed. The microstimulator hasa structure that is manufactured to be substantially encapsulated withina hermetically sealed housing inert to body fluids, and of a size andshape capable of implantation in a living body, with appropriatesurgical tools. Within the microstimulator, an induction coil receivesenergy from outside the body requiring an external power supply.

In yet another example, U.S. Pat. No. 6,185,452, which patent islikewise incorporated herein by reference, there is disclosed a deviceconfigured for implantation beneath a patient's skin for the purpose ofnerve or muscle stimulation and/or parameter monitoring and/or datacommunication. Such a device contains a power source for powering theinternal electronic circuitry. Such power supply is a battery that maybe externally charged each day. Similar battery specifications are foundin U.S. Pat. No. 6,315,721, which patent is additionally incorporatedherein by reference.

Other microstimulator systems prevent and/or treat various disordersassociated with prolonged inactivity, confinement, or immobilization ofone or more muscles. Such microstimulators are taught, e.g., in U.S.Pat. No. 6,061,596 (Method for Conditioning Pelvis Musculature Using anImplanted Microstimulator); U.S. Pat. No. 6,051,017 (ImplantableMicrostimulator and Systems Employing the Same); U.S. Pat. No. 6,175,764(Implantable Microstimulator System for Producing Repeatable Patterns ofElectrical Stimulation; U.S. Pat. No. 6,181,965 (ImplantableMicrostimulator System for Prevention of Disorders); U.S. Pat. No.6,185,455 (Methods of Reducing the Incidence of Medical ComplicationsUsing Implantable Microstimulators); and U.S. Pat. No. 6,214,032 (Systemfor Implanting a Microstimulator). The applications described in theseadditional patents, including the power charging techniques, may also beused with the present invention. The '596, '017, '764, '965, '455, and'032 patents are incorporated herein by reference.

It is also known in the art to use thermal energy to power an at leastpartially implantable device, as taught in U.S. Pat. No. 6,131,581, alsoincorporated herein by reference, wherein an implantable thermoelectricenergy converter is disclosed.

Despite the various types of microstimulators known in the art, asillustrated by the examples cited above, significant improvements arestill possible and desirable, particularly relative to a microstimulatorwith a self-contained primary or rechargeable battery that: (a) canaccommodate the various needs of a microstimulator; (b) can accommodatevarious locations in the implanted site; and/or (c) can allow themicrostimulator to operate longer between charges or replacement.

SUMMARY OF INVENTION

The present invention addresses the above and other needs by providing abattery-powered microstimulator intended to provide therapy forneurological disorders such as urinary urge incontinence by way ofelectrical stimulation of nerve fibers in the pudendal nerve; to treatvarious disorders associated with prolonged inactivity, confinement, orimmobilization of one or more muscles; to be used as therapy forerectile dysfunction and other sexual dysfunction; as a therapy to treatchronic pain; and/or to prevent or treat a variety of other disorders.The invention disclosed and claimed herein provides such abattery-powered microstimulator and associated external components.

Stimulation and control parameters of the implanted microstimulator arepreferably adjusted to levels that are safe and efficacious with minimaldiscomfort. Different stimulation parameters have different effects onneural tissue, and parameters may be chosen to target specific neuralpopulations and to exclude others. For example, relatively low frequencyneurostimulation (i.e., less than about 50-100 Hz) may have anexcitatory effect on surrounding neural tissue, leading to increasedneural activity, whereas relatively high frequency neurostimulation(i.e., greater than about 50-100 Hz) may have an inhibitory effect,leading to decreased neural activity.

In accordance with certain embodiments of the invention, there isprovided a microstimulator sized to contain a self-contained powersource, e.g., a primary battery. In another embodiment, theself-contained power source comprises a battery that is rechargeable byan external power source, e.g., an RF link, an inductive link, or otherenergy-coupling link. In yet other embodiments, the power source maycomprise other energy sources, such as a super capacitor, a nuclearbattery, a mechanical resonator, an infrared collector (receiving, e.g.,infrared energy through the skin), a thermally-powered energy source(where, e.g., memory-shaped alloys exposed to a minimal temperaturedifference generate power), a flexural powered energy source (where aflexible section subject to flexural forces is placed in the middle ofthe long, thin-rod shape of the microstimulator), a bioenergy powersource (where a chemical reaction provides an energy source), a fuelcell (much like a battery, but does not run down or require recharging,but requires only a fuel), a bioelectrical cell (where two or moreelectrodes use tissue-generated potentials and currents to captureenergy and convert it to useable power), an osmotic pressure pump (wheremechanical energy is generated due to fluid ingress), or the like.

For purposes of the present invention, the term “self contained” meansimplanted within the patient and not totally dependent upon external(non-implanted) sources of energy. Typically, the self-contained powersource will be contained within a housing, e.g., the same housing as theone that contains the electronic circuits of the implantable device,that is implanted within the patient or user of the device. A keyfeature of the self-contained power source is that it is not dependentupon a continuous source of external (non-implanted) power. Theself-contained power source used with the invention may rely upon anoccasional use of an external power source, e.g., an occasional burst orinfrequent injection of energy to replenish the self contained powersource, such as a rechargeable battery or super capacitor, but the “selfcontained” power source may thereafter operate on its own to provideneeded power for operation of the device without being connected orcoupled to the external source of power.

In accordance with various embodiments of the invention, there isprovided a microstimulator with at least two electrodes for applyingstimulating current to surrounding tissue and associated electronicand/or mechanical components encapsulated in a hermetic package madefrom biocompatible material. The internal components are powered by theinternal power source. The internal power source is, in one preferredembodiment, a primary battery, and in another preferred embodiment, arechargeable battery. In other embodiments, the energy source may takethe form of any of the various energy sources mentioned above, orcombinations thereof.

Some embodiments of the invention provide a microstimulator with meansfor receiving and/or transmitting signals via telemetry, such as meansfor receiving and/or storing electrical power within the microstimulatorand for receiving and/or transmitting signals indicating the chargelevel of the internal battery. Certain embodiments of the inventionprovide a microstimulator implantable via a minimal surgical procedureand the associated surgical tools. Methods of manufacturing/assemblingthe components within the microstimulator, including the internalbattery or other power source, ferrite material, induction coil, storagecapacitor, and other components using e.g., conductive andnon-conductive adhesives, are described herein. Also described hereinare methods of externally coating the hermetically sealed cylindricalhousing to protect the internal components.

Embodiments described herein may include some or all of the itemsmentioned above. Additional embodiments will be evident upon furtherreview of the present disclosure.

BRIEF DESCRIPTION OF DRAWINGS

The above and other aspects of the present invention will be moreapparent from the following more particular description thereof,presented in conjunction with the following drawings wherein:

FIG. 1 is a block diagram for an exemplary battery-powered BION (BPB)system made in accordance with the present invention;

FIG. 2 shows a representative biphasic electrical current stimulationwaveform that may be produced by the battery-powered BION system of thepresent invention;

FIGS. 3A and 3B shows a table summarizing exemplary battery-powered BIONstimulation parameters;

FIG. 4 is an enlarged side view showing the overall descriptivedimensions for the battery-powered BION case, the battery, and theelectronic subassembly;

FIG. 5 is a perspective view of the battery and connecting wires;

FIG. 6 is a block diagram representing the battery states based onmeasured battery voltage;

FIG. 7 is a front view of a representative remote control panel showingexemplary front panel components;

FIG. 8 is an exploded view of the internal components of the BPB device;

FIG. 9 is a perspective top view of the internal electronic panel in abatch configuration;

FIG. 10 is a perspective top view of the panel shown in FIG. 9 with theintegrated circuitry attached;

FIG. 11A is a perspective top view of the panel shown in FIG. 9 with theintegrated circuitry shown in FIG. 10 and with the top capacitors anddiodes attached;

FIG. 11B is an enlarged detailed view of a portion of FIG. 11A, showingin greater detail the attachment of the top capacitors and diodes;

FIG. 12 is a perspective top view of the panel shown in FIG. 9 with theintegrated circuitry shown in FIG. 10, the top capacitors and diodesshown in FIG. 11A, and with the top ferrite half attached;

FIG. 13 is an enlarged detail view of the assembled components shown inFIG. 12 depicting the connecting electrical wires;

FIG. 14A is a perspective top view of a sub-assembly assembled duringthe manufacturing operation;

FIG. 14B is a bottom perspective view of the sub-assembly shown in FIG.14A;

FIG. 14C is a top plan view of the sub-assembly shown in FIG. 14A;

FIG. 14D is a bottom plan view of the sub-assembly shown in FIG. 14A;

FIG. 15A is a perspective top view of the sub-assembly shown in FIG. 14Awith a coil wound on the middle section of the ferrite cylinder;

FIG. 15B is a cross-section view of the sub-assembly shown in FIG. 15Ataken along line 15B-15B;

FIG. 15C is a top view of the sub-assembly shown in FIG. 14A with thecoil ends depicted;

FIG. 16 is an enlarged detail perspective view of the sub-assembly shownin FIG. 15A placed in a soldering fixture;

FIG. 17 is an exploded view of carrier fixture plates;

FIG. 18 is a perspective view of a supporting work-plate with one of thecarrier plates shown in FIG. 17 and the sub-assembly shown in FIG. 15A;

FIG. 19 is a perspective view of the sub-assembly shown in FIG. 15A witha battery attached and also depicting assembled internal components of aBPB device of the present invention;

FIG. 20A is a top view of a BPB device of the present invention showingexternal coatings;

FIG. 20B is a cross-sectional view taken along line 20B-20B shown inFIG. 20A;

FIG. 20C is an end view of the BPB device shown in FIG. 20A; and

FIG. 21 is an exemplary circuit block diagram showing the mainimplantable components and their interactions of one embodiment of theinvention.

Corresponding reference characters indicate corresponding componentsthroughout the several views of the drawings.

DESCRIPTION OF EMBODIMENTS

The following description is of the best mode presently contemplated forcarrying out the invention. This description is not to be taken in alimiting sense, but is made merely for the purpose of describing thegeneral principles of the invention. The scope of the invention shouldbe determined with reference to the claims.

A fully assembled battery-powered microstimulator (also referred to as aBION® microstimulator, or battery-powered BION (“BPB”) device) made inaccordance with the present invention may operate independently, or in acoordinated manner with other implanted devices, or with externaldevices.

The BPB device is a pulse generator that includes an internal powersource. Regardless of whether the internal power source comprises aprimary battery, a rechargeable battery, or an alternative power sourceas described below, the device containing the internal power source willbe referred to as a “BPB” device for purposes of the present invention.

In one preferred embodiment, the power source comprises a rechargeablebattery. The battery is recharged, as required, from an external batterycharging system, typically through an inductive link.

In another preferred embodiment, the power source comprises a primarybattery. A primary battery, or primary battery cell, offers theadvantage of typically having five to ten times more energy density thandoes a rechargeable battery. Further, a primary battery typicallyexhibits a much lower self-leakage than does a rechargeable battery.

In other embodiments of the invention, the power source of the BPBdevice comprises an alternative energy source, or a combination ofalternative energy sources. One such alternative energy source is asuper capacitor. A super capacitor typically has ten times less energydensity than does a rechargeable battery, but it can be recharged veryquickly, thus allowing for the use of a simple combination RC andcharger system. Additionally, power coupled inductively to a supercapacitor storage element may enable pulsed radio frequency (RF) powerto be used, rather than continuous RF power. A super capacitor istypically used, most advantageously, in combination with another powersource, such as a primary battery or a rechargeable battery. The supercapacitor may be charged rapidly, and then the charge stored on thesuper capacitor is available to supplement operation of the BPB device,either directly (to assist with higher energy stimulation levels orpower requirements), or indirectly (to help recharge the battery).

A further alternative energy source that may be used with the BPB deviceof the invention is a nuclear battery, also known as an atomic battery.Recent developments have indicated that, e.g., amicro-electro-mechanical system (MEMS) nuclear battery is capable ofdelivering significant amounts of power. These power sources areextremely small, and may be combined or grouped together, as required,in order to provide the needed power to operate the BPB device.

Still another alternative energy source that may be used with the BPBdevice is a mechanical resonator. Generating power from mechanicalresonators and normal human movement has long been practiced in the art,e.g., with wristwatches, and MEMS versions of such resonators have beenaround for a number of years. However, to applicants' knowledge, the useof MEMS mechanical resonators has never been applied to implantabledevices, such as the BPB device of the present invention.

A further alternative energy source for use with a BPB device is aninfrared collector, or infrared (solar) power source. Because the skinand body tissue is relatively transparent to red and infrared light, itis possible, e.g., through the use of an implanted silicon photovoltaiccell, to collect sufficient energy to power the BPB device from anexternal infrared source, such as the sun.

Yet an additional alternative energy source for use with the BPB deviceof the present invention is a thermally powered energy source. Forexample, thermal difference engines based on memory shape alloys havebeen demonstrated to be very efficient engines capable of generatingpower with minimal temperature differences. Hence, by incorporating sucha thermal difference engine within the BPB device, an internal energysource is provided that derives its energy from a small temperaturedifference, e.g., the temperature difference between the surface of theskin and a location 2-3 cm deeper inside the body.

Still another alternative energy source is a flexural powered energysource. The BPB device has the general shape of a long thin rod. Hence,by placing a flexible section in the middle of the device, such sectionwill be subjected to flexural forces. Such flexural forces, when appliedto a suitable piezoelectric element coupled to the flexible section,will generate piezoelectric bimorphs that may be used to generate avoltage (power). Such technique has been used to generate power fromwind.

Another alternative energy source is a bioenergy power source. In abioenergy power source, a chemical reactor interacts with constituentsto produce mechanical or electrical power.

A fuel cell represents another type of alternative energy source thatmay be used with the BPB device. A fuel cell, in principle, operatesmuch like a battery. Unlike a battery, however, a fuel cell does not rundown or require recharging. Rather, it produces energy in the form ofelectricity and heat as long as fuel is supplied. A fuel cell systemthat includes a “fuel reformer” can utilize the hydrogen from anyhydrocarbon fuel. Several fuel cell technologies may be used with theBPB device of the present invention, such as Phosphoric Acid, ProtonExchange Membrane or Solid Polymer, Molten Carbonate, Solid Oxide,Alkaline, Direct Methanol, Regenerative, Zinc Air, or Protonic Ceramic.Such fuel cells may be designed for a single use, or refillable.

Yet an additional alternative energy source that may be used with theBPB device is a bioelectrical cell. In a bioelectrical cell, a set ofelectrodes (two or more) is implanted in the body tissue. Theseelectrodes sense and use tissue generated potentials and currents inorder to power the BPB device. Tissue such as cardiac muscle, cardiacconducting cells and neural tissue are examples of tissue that generateselectrical potentials and currents. In a particular case, specializedbiological tissue may be implanted to provide the energy. The implantedbiological tissue remains alive due to the environment provided by thebody where it is implanted.

A further alternative energy source that may be used with the BPB deviceof the present invention is an osmotic pressure pump. Osmotic pressurepumps may be used to generate mechanical energy due to water, or otherfluid, ingress. This mechanical energy may then be used to generateother forms of energy, such as electrical energy. For example, osmoticpressure may be used to separate the plates of a capacitor. As theplates of the capacitor separate with a given amount of charge due toosmotic pressure, the energy stored in that capacitor is incremented.

In the description of the BPB device that follows, the power source usedwithin the BPB device is described as a rechargeable battery. However,it is to be understood, as previously indicated, that the “power source”used within the BPB device may take many forms, including a primarybattery or the alternative power sources enumerated above, and that whenthe term “battery” or “power source” is used herein, such terms, unlessotherwise indicated, are meant to broadly convey a source of energy orpower contained within, or coupled to, the BPB device.

The BPB device preferably has a substantially cylindrical shape,although other shapes are possible, and at least portions of the BPBdevice are hermetically sealed. The BPB device includes a processor andother electronic circuitry that allow it to generate stimulus pulsesthat are applied to a patient through electrodes in accordance with aprogram that may be stored, if necessary or desired, in programmablememory.

The BPB device circuitry, power source capacity, cycle life,hermeticity, and longevity provide implant operation at typical settingsfor at least five years. Battery or power source) control circuitryprotects the battery or other power source from overcharging, ifrecharging is needed, and operates the BPB device in a safe mode uponenergy depletion, and avoids any potentially endangering failure modes,with a zero tolerance for unsafe failure or operational modes. The BPBdevice accepts programming only from compatible programming devices.

The publications and patents listed in the table below, which are allincorporated herein by reference, describe various uses of theimplantable BPB device for the purpose of treating various neurologicalconditions: U.S. Pat. No. 6,061,596, issued May 9, 2000, entitled“Method for Conditioning Pelvic Musculature Using an ImplantedMicrostimulator”; U.S. Pat. No. 5,193,540, issued Mar. 16, 1993,entitled “Structure and Method of Manufacture of an ImplantableMicrostimulator”; PCT Publication WO 00/01320, published Jan. 13, 2000,entitled “Implantable Stimulator System and Method for Treatment ofUrinary Incontinence”; PCT Publication WO 97/18857, published May 29,1997, entitled “System and Method for Conditioning Pelvic MusculatureUsing an Implanted Microstimulator.”

The implantable BPB system of the present invention, in accordance withsome embodiments, includes internal and external components, as well assurgical components, as shown in FIG. 1. The internal components 10′ areimplanted in the target tissue area of the patient and the externalcomponents 20 are used to recharge or replenish (when recharge orreplenishment is needed) and communicate with the internal components.The components shown in FIG. 1 represent as a whole an implantable BION®microstimulator system 100. It should be noted that the presentinvention is not directed to a specific method for treating a disorder,but rather describes possible BPB configurations, methods ofmanufacture, and how the implantable BPB system functions in conjunctionwith the components shown in FIG. 1.

A block diagram that illustrates the various components of the BPBsystem 100 is depicted in FIG. 1. These components may be subdividedinto three broad categories: (1) implantable components 10′, (2)external components 20, and (3) surgical components 30.

As seen in FIG. 1, the BPB device 10 includes a case 12; battery 16; BPBelectronic subassembly 14, which includes BPB coil 18 and a stimulatingcapacitor CSTIM 15; indifferent/reference electrode 24; andactive/stimulating electrode 22. The block diagram shown in FIG. 21 alsoshows the main implantable components of the BPB device 10 and theirinteractions.

The external components 20, shown in FIG. 1 include charging system 39,which consists of the chair pad 32 and the base station 50; a remotecontrol 40; and a clinician's programmer 60. The chair pad 32 has arecharger coil 34 that is electrically connected to (or may be part of)the base station 50 with extension 36 and communicates with the BPBelectronic subassembly 14 with a bidirectional telemetry link 48. Thebase station 50 has an external medical grade AC adapter that receivesAC power 52 through extension 54. The remote control 40 sends andreceives communication from/to the base station 50 through Infrared DataAssociation, IrDA interface 42. (IrDA is a standard for transmittingdata via infrared light.) The remote control 40 also communicates withthe clinician's programmer 60 through an IrDA interface 44 andcommunicates with the BPB electronic subassembly 14 with an RF telemetryantenna 46 through the bidirectional telemetry link 48. The clinician'sprogrammer 60 may also communicate with the BPB electronic subassembly14 through the bidirectional telemetry link 48. The base station 50 alsocommunicates with the clinician's programmer 60 through an IrDAinterface 45. The bidirectional telemetry link 48 is also known as theFSK (Frequency Shift Key) telemetry link, or RF telemetry link. Inaddition, the charging system 39 has a forward telemetry link 38. Suchlink may use OOK-PWM (On/Off Keying-Pulse Width Modulation), and istypically an inductive telemetry link. When used, both power andinformation may be transferred to the BPB device. When charging is notneeded, e.g., when the battery comprises a primary battery, such aninductive link may still be used to transfer information and data to theBPB device.

The surgical components 30 illustrated in FIG. 1 include the BPB implanttools 62 and an external neurostimulator 64. The implantable BPB device10 is inserted through the patient's tissue through the use ofappropriate surgical tools, and in particular, through the use oftunneling tools, as are known in the art, or as are specially developedfor purposes of implantable BPB stimulation systems.

FIG. 1 represents the BPB system 100 as a block diagram that aids insimplifying each of the described implantable components 10′, externalcomponents 20, and surgical components 30. A better understanding of thepossible functions associated with every element of the internalcomponents 10′, external components 30, and surgical components 30 isprovided in the details that follow.

Turning next to FIG. 2, an exemplary waveform is shown that illustratessome of the BPB biphasic electric current stimulation parameters. Otherparameters not shown include burst, ramp, and duty cycles. The BPBdevice 10 may produce, for instance, an asymmetric biphasicconstant-current charge-balanced stimulation pulse, as shown in FIG. 2.Charge balancing of the current flow through the body tissue in bothdirections is important to prevent damage to the tissue that resultsfrom continued preponderance of current flow in one direction. The firstphase of the stimulation pulse is cathodic and the second phase(recharge phase) utilizes an anodic charge recovery to facilitate acharge balance. The stimulation phase current amplitude 66 isprogrammable from 0.0 to about 10 mA, for instance, in 0.2 mAincrements. To prevent patient discomfort due to rapidly increasing ordecreasing amplitudes in the first phase of the waveform (of stimulationamplitude 66), changes in amplitude occur smoothly over a transitionperiod programmable by adjusting the allowed slope (step sizeincrements) of the amplitude through continuous pulses.

The stimulation capability of the BPB device 10 is depicted by thestimulation parameters specified in the table shown in FIGS. 3A and 3B.These parameters may be achieved by the electronic subassembly 14,battery (or other power source) 16, and electrodes 22 and 24. Thestimulating electrode 22 is coupled to the electronic subassembly 14with a stimulating capacitor CSTIM 15. Net DC charge transferred duringstimulation is prevented by the capacitive coupling provided by thestimulating capacitor 15, between the BPB electronic subassembly 14 andthe stimulation electrode 22. During the first phase of the pulsewaveform shown in FIG. 2, the BPB stimulation electrode 22 has acathodic polarity with associated negative current amplitude, and thereference electrode 24 is the anode.

Each BPB device 10 has an identification code used to identify thedevice uniquely. The identification code allows each unit to act onparticular messages containing its unique identification code. Each BPBdevice 10 also responds to universal identification codes used for casesin which the unique address is unknown by the external device, theunique address has been corrupted, or when a command is sent to multipleBPB units.

Referring back to FIG. 1, the BPB device 10 receives commands and datafrom the remote control 40, clinician's programmer 60, and/or chargingsystem 39 via FSK (frequency shift keying) telemetry link 48. The rangeof the FSK telemetry link 48 is no less than 30 cm in an optimalorientation. Factors that may affect the range of the FSK telemetry link48 include an impaired BPB device, depleted external device,insufficient power, environmental noise, and other factors, e.g., thesurroundings. When a request is sent to the BPB device 10 by theclinician's programmer 60, the remote control 40, or the charging system39, the maximum response time for the FSK telemetry link 48 is less than2 seconds, under normal operating conditions.

The OOK (On-Off Keying) telemetry link 38, shown in FIG. 1, allowscommands and data to be sent by the charging system 39 to the BPB device10. The range of the OOK telemetry link 38 is ideally no less than 15 cmin any orientation and no less than 15 cm in an optimal orientation. TheOOK telemetry link 38 allows the charging system 39 to communicate withthe BPB device 10 even when the BPB device 10 is not actively listeningfor a telemetry signal, e.g., when the BPB device 10 is in theHibernation State or the Storage State (states for the BPB device thatwill be discussed in detail below). The OOK-PWM telemetry link 38 willalso provide a communication interface in an emergency situation, e.g.,an emergency shutdown.

Reverse telemetry is also available through the FSK telemetry link 48.The reverse FSK telemetry link 48, allows information to be reported bythe BPB device 10 to the clinician's programmer 60, the remote control40, and/or the charging system 39. The range of the reverse telemetrylink 48 is no less than 30 cm in an optimal orientation. The type ofinformation transmitted from the BPB device 10 to the clinician'sprogrammer 60, remote control 40, and/or charging system 39, may includebut is not limited to battery voltage, BPB internal register settings,and acknowledgments.

The FSK telemetry system, in one preferred embodiment, operates in thefrequency band of 127 KHz.+/−8 KHz. When the BPB device 10 has receiveda valid (i.e. non-error containing) message, an acknowledgment istransmitted.

There will be times when the messages sent in either direction on thetelemetry link will not be received by the intended recipient. This maybe due to range, orientation, noise, or other problems. The severity ofthe problem will determine the appropriate response of the system. Forexample, if a programming change is made by the clinician's programmer60 and a response is expected by the clinician's programmer 60 from theBPB device 10, the clinician's programmer 60 attempts to get a responsefrom the BPB device 10 until a satisfactory response is received, oruntil a reasonable number of attempts are made. If no satisfactoryresponse is obtained, this might indicate that the BPB device 10 doesnot have sufficient power in its internal battery 16 to make a response,in which case charging should be attempted by the user (if the battery16 is a rechargeable battery). Events such as these are logged forfuture diagnostic analysis. Error messages are displayed on theclinician's programmer 60, the remote control 40, and/or the basestation 50, in response to an abnormal response to telemetrycommunication. When an invalid command is received by BPB device 10, noaction occurs. All valid commands are executed by the BPB device 10within 1 second after receiving a command, under normal operatingconditions.

Referring now to FIG. 4, a side view of the BPB case 12 is showndepicting exemplary overall dimensions for the case 12 and BPB internalcomponents. The BPB case 12 functions together with the additionalcomponents of BPB device 10, including the BPB battery 16 and the BPBelectronic subassembly 14. As shown in the figures, BPB case 12 may havea tubular or cylindrical shape with an outer diameter shown in FIG. 4 asD1 having a minimum value of about 3.20 mm and a maximum value of 3.7mm, and preferably a maximum value of about 3.30 mm. The inner diameterof the portion of the BPB case 12 enclosing the electronic subassembly14 is shown in FIG. 4 as D2 with a minimum value of about 2.40 mm and amaximum value of about 2.54 mm. The inner diameter of the portion of theBPB case 12 enclosing the BPB battery 16 is shown in FIG. 4 as D3 with aminimum value of about 2.92 mm and a maximum value of about 3.05 mm. Thelength of the BPB case 12 is shown in FIG. 4 as L1 with and is nogreater than about 30 mm, and preferably no greater than about 27 mm (L1includes the length of the case housing plus the stimulating electrode22). The length L2 of the case 12 has a value of about 24.5 mm. Theportion of the case 12 enclosing the electronic subassembly 14 is shownin FIG. 4 as length L3 with a maximum value of about 13.00 mm. Theportion of the case 12 enclosing the BPB battery (or other power source)16 is shown in FIG. 4 as length L4 with a value of about 11.84 mm. Thesedimensions are only exemplary, and may change, as needed or desired toaccommodate different types of batteries or power sources. For example,the BPB device, instead of being cylindrically shaped, may have arectangular or oval cross section having a width and height that is nogreater than about 3.3 mm, and an overall length is no greater thanabout 27 mm. To help protect the electrical components inside the BPBdevice 10, the case 12 of the BPB device 10 is hermetically sealed. Foradditional protection against, e.g., impact, the case 12 may be made ofmetal (e.g., titanium), which material is advantageously biocompatible.The BPB case 12 is preferably, but not necessarily, Magnetic ResonanceImaging (MRI) compatible. The manufacturing/assembly process of the BPBdevice 10 will be discussed in detail below.

The BPB device 10 includes a battery 16. The battery 16 may be a primarybattery, a rechargeable battery, or other power source, as previouslydescribed. When the battery 16 is rechargeable, it is recharged, asrequired, from an external battery charging system 39 typically throughthe OOK-PWM telemetry link 38 (as shown in FIG. 1).

The BPB device 10 includes a processor and other electronic circuitrythat allow it to generate stimulating pulses that are applied to apatient through electrodes 22 and 24 in accordance with a program storedin programmable memory located within the electronic subassembly 14.

The battery 16 shown in FIG. 5 is a self-contained battery that powersthe BPB device 10. The battery 16 may be a Lithium-ion battery or othersuitable type of battery or power source. One type of rechargeablebattery that may be used is disclosed in International Publication WO01/82398 A1, published 1 Nov. 2001, and/or WO 03/005465 A1, published 16Jan. 2003, which publications are incorporated herein by reference.Other battery construction techniques that may be used to make thebattery 16 used with the BPB device are as taught, e.g., in U.S. Pat.Nos. 6,280,873; 6,458,171 and U.S. Publications 2001/0046625 A1 and U.S.2001/0053476 A1, which patents and publications are also incorporatedherein by reference. Recharging (when needed) occurs from an externalcharger to an implant depth, e.g., up to 13.87 cm. At this distance,charging from 10% to 90% capacity can occur in no more than eight hours.The battery 16 functions together with the additional components of theBPB device 10, including the BPB case 12 and the BPB electronicsubassembly 14 to provide electrical stimulation through the electrodes22 and 24. The battery or power source 16 has a pin 95 protruding fromthe flat end for the positive polarity contact. This pin has aprotruding length, e.g., of 0.25 mm and is embedded internallythroughout the length of the cathode case of the battery 16. The pin 95may be made of platinum or other suitable anode material. Wires 68A and68B are used for connecting the battery 16 to the electronic subassembly14. Wire 68A is insulated and laser welded or otherwise electricallyconnected to the pin 95, and wire 68B is not insulated and is laserwelded or otherwise electrically connected to the case of the battery.The battery case 70 has a negative polarity. The battery's nominalvoltage is typically 3.6 V, measured during a first cycle C/5 discharge.The battery's nominal capacity, C, is no less than 2.5 mAh(milli-amp-hours) when measured after the third discharge cycle with C/2charge to 4.0V and C/5 discharge to 3.0V at 37 degrees C. (C/2 chargemeans that it takes 2 hours for the battery 16 to charge. C/5 dischargemeans that it takes 5 hours for the battery 16 to discharge.) Charge ordischarge time is calculated by taking the capacity (mAh or Ah) anddividing it by current (mA or A). The nominal settings are 4 mAamplitude, 20 Hz pulse frequency, 200 μsec pulse width, 5 sec burst-on,5 sec burst-off, and 200 μA recovery into a 1000 ohm resistive load.

The electronic subassembly 14, shown in FIG. 1, functions together withthe additional components of the BPB device 10, including the BPB case12, BPB battery 16, and electrodes 22 and 24, to provide the BPB devicestimulating function. In one preferred embodiment, the electronicsubassembly 14 fits within, for instance, a cylinder with an outerdiameter D2 and length L3 as shown in FIG. 4. The inner diameter D2 hasa minimum value of about 2.40 mm and a maximum value of about 2.54 mm.The length L3 has a maximum value of about 13.00 mm.

The electronic subassembly 14 contains circuitry for stimulation,battery charging (when needed), telemetry, production testing, andbehavioral control. The stimulation circuitry can be further dividedinto components for high voltage generation, stimulation phase currentcontrol, recovery phase current control, charge balance control, andover voltage protection circuitry. The telemetry circuitry can befurther divided into an OOK receiver, FSK receiver, and FSK transmitter.The behavioral control circuitry can be further divided into componentsfor stimulation timing, high voltage generation closed loop control,telemetry packet handling, and battery management. In addition to thesefunctions, there is circuitry for reference voltage and referencecurrent generation, system clock generation, and Power-On Reset (POR)generation. The coil 18 (shown in FIG. 1) is utilized for receivingpower for battery charging (when used), telemetry, and high voltagegeneration.

The charging circuitry within the electronic subassembly 14 detects thepresence of an external charging field within no more than 5 seconds ofthe application of such a field. Upon detection, the BPB device 10enables a mode in which it can receive a telemetry message and in whichit can recharge the battery 16, as necessary. The electronic subassembly14 measures the rectified voltage during recharging and is able totransmit the measured voltage value to the base station 50 via coil 34.The battery voltage measurements are made in relatively identicalconditions. Specifically, the battery voltage is measured when nostimulation pulse is being delivered.

When the BPB device utilizes a rechargeable battery, and when thevoltage is less than the voltage defined by the Battery Recharge UpperVoltage Limit Internal Register (BRUVLIR), the BPB device 10 charges thebattery 16 using constant current charging with a maximum current ofC/2. The constant current phase of charging ends and the constantvoltage phase of charging begins when the BPB voltage reaches thevoltage defined by the BRUVLIR.

During the constant voltage phase of charging, the charging circuitrymaintains the battery 16 charging voltage at the voltage defined by theBRUVLIR. When the constant voltage charging current falls to 400 μA orless (i.e., when full charge has been reached), the charge ready bit ofthe BPB status register is activated and charging may be completed bythe removal of the magnetic field. During charging, the BPB chargingcircuitry monitors the incoming magnetic energy and periodically sendsinformation to the base station 50 via coil 34 in order to minimize themagnetic field that the BPB device 10 is exposed to, thus minimizing theelectrical dissipation of the BPB device 10 while charging. U.S. Pat.No. 6,553,263, incorporated herein by reference, describes relevantcharging technology that may also be used.

Protection circuitry within the electronic subassembly 14 is used as afailsafe against battery over-voltage. A battery protection circuitcontinuously monitors the battery's voltage and electrically disconnectsthe battery if its voltage exceeds 4.1 V. The BPB device 10 is not ableto recover from an excessive voltage condition, and thus requiresexplantation should an over-voltage condition occur, where anover-voltage condition is defined as a voltage that exceeds 4.1 V.

The BPB device 10 has different states based on the measured batteryvoltage, Vbatt. (Vbatt is measured when no stimulation is beingdelivered). FIG. 6 represents these various states and transitionsbetween states. The BPB device 10 should normally be in Normal OperationState 102, but when the measured battery voltage, Vbatt, falls below thevoltage defined by the battery voltage hibernation level internalregister, VHIB, the device enters a low-power Hibernation State 104.VHIB is a programmable voltage value of hibernation threshold for thebattery 16. In the Hibernation State, stimulation and FSK telemetry arediscontinued. In other words, the BPB device 10 discontinues listeningfor an incoming FSK telemetry signal but continues to listen for anincoming OOK telemetry signal. In the Hibernation State 104, the BPBdevice 10 is able to detect an applied external charging field. TheHibernation State 104 persists until the battery voltage, Vbatt, exceedsthe programmable value of VHIB, where VHIB is programmable between 3.25V and 3.6 V. The battery 16 then goes back to Normal Operation State 102and the stimulation and FSK telemetry signals resume when Vbatt becomesgreater than the programmed value+/−0.05 V.

While in the Hibernation State 104, the battery 16 may also enter theDepletion State 106 when Vbatt falls below a non-programmable voltagevalue of Power On Reset (VPOR) threshold for the battery 16 of between2.2V and 2.8V. In the Depletion State 106, the stimulation and FSKtelemetry are discontinued and are only able to be resumed followingprogramming and recharging by a clinician. The BPB device 10 disablesall circuitry except what is required for recharging the battery when anRF charging field is applied. While in the Depletion State 106, the BPBcircuitry is able to recharge the battery 16 from an external chargingfield. Charging while in the Depletion State 106 is performed at a slowrate (trickle charge) to allow the battery to recover from a low voltagecondition. The BPB device 10 performs a power-on reset when Vbattexceeds VPOR, then the BPB device 10 returns back to the HibernationState 104.

The BPB device 10 can also be set in Storage Mode 108. In Storage Mode108, the BPB device 10 shuts down the circuitry in order to conservepower and the stimulation and FSK telemetry is disabled. In Storage Mode108, the BPB device 10 is able to detect a charging field and is able toreceive both power for recharging as well as OOK telemetry messages viaa charging field.

The BPB device 10 contains an inductive coil 18 utilized for receivingpower and telemetry messages through an inductive telemetry link 38. Thecoil 18 may also be utilized to implement additional functions,including voltage conversion. The BPB coil 18 contained in theelectronic subassembly 14 has an exemplary cylindrical shape and isconstructed from multiple turns of conductive wire around a two-pieceexemplary dumbbell shaped ferrite core. Assembly of the BPB coil 18,internal electronic components, and the two-piece ferrite core will bediscussed in more detail presently.

Turning back to FIG. 1, the remote control 40 provides clinicianprogramming of the BPB device 10 and limited stimulation control for thepatient following implantation via a bidirectional FSK telemetry link48. (As stated earlier, an IrDA direct link 44 is provided to interfacebetween the clinician's programmer 60 and the remote control 40). Theremote control 40 is small and light enough to be held comfortably inone hand and fits inside a purse or pocket. Its smallest dimension is nomore than 3 cm and its largest dimension is no more than 11.5 cm. Theremote control 40 operates on standard (e.g., off-the-shelf) batteries,such as AAA batteries.

An exemplary front panel 114 of the remote control 40 is shown in FIG.7, which identifies the primary control keys. An LCD display 116 showsall values and messages, e.g., whether stimulation is enabled ordisabled or the battery's energy level or state (normal, hibernation,depletion, or storage). The following control keys are found in thefront panel 114: ON/OFF key 118, up arrow key 120, down arrow key 122,information key 123, and status key 124. All control keys are easilymanipulated and may be recessed so that they are not accidentallyactivated (e.g., when the remote control 40 is in a purse).

The Clinician's Programmer (CP) 60 controls an implanted BPB device 10by communicating with an External Controller (the Remote Control 40 orcharging system 39). External Controller 39 or 40 in turn conveyscommands to the BPB device 10 through an FSK telemetry link 48. Aclinician has three ways to start up the CP program: “New Patient”,“Find Patient,” and “Scan for BION.” The “New Patient” option brings upa blank form for the clinician to fill in the patient demographicinformation such as name, birth date, identifying number, address,contact information, and notes. The “Find Patient” option brings up amenu of previously entered patient records for selection. Upon selectionof a patient, the saved patient information is displayed for review. The“Scan for BION” option determines whether there is a BPB device 10within telemetry range. If so, the identification number (ID) of the BPBdevice 10 is obtained and the database is searched for a patient whoseimplanted BPB device 10 ID matches the one found. If such a match isfound, the patient's demographic information is automatically displayedfor review.

Once a patient for the BPB device has been identified, the clinician canthen adjust stimulation parameters through the Parameter Test utility.The successful stimulation parameter sets can be saved to the patient'srecord in the database. Previously saved parameter sets can be reviewedand re-applied using utilities to view history or current settings. Thecurrent battery level of the BPB device 10, as well as records of therecharge times, can be viewed.

The Clinician's Programmer 60 may also be used to generate differenttypes of reports, such as Patient Information, Session Summary, ImplantSystem, and Visit History. The Patient Information report includes allof the patient's demographic information. The Session Summary reportsummarizes the events for the follow-up session. The Implant Systemreport details the information for the implanted BPB device 10 and anyexternal controllers assigned to the patient. The Visit History showsinformation about office visits for the patient in the desired daterange. The Clinician's Programmer 60 includes utilities to backup andrestore the database. A utility is also available for exporting selectedpatient information into a data format for transfer.

As described earlier, the charging system 39 shown in FIG. 1, whichincludes the base station 50 and the chair pad 32, is used totranscutaneously charge the BPB battery 16 (when needed), and it is alsoused to communicate with and control the BPB device 10 via an OOKtelemetry link 38 and/or an FSK bidirectional telemetry link 48. Most ofthe electronics of charging system 39 are housed in a stand-alonepackage, with the exception of an AC adapter 54 for connection with awall AC power socket 52. The charging system 39 also provides feedbackto the user regarding the status of the BPB battery 16 duringrecharging. The remote control 40 and the clinician's programmer 60 maybe linked via an IrDA interface 45 to the charging system 39 tofacilitate exchange of data.

An exemplary manufacturing/assembly process of the BPB device 10 willnext be described. Unassembled BPB internal components 200 are shown inFIG. 8 and their interactions once assembled are depicted in thefunctional block diagram of FIG. 21. The components 200 include panel202; integrated circuitry 206; capacitors 208A1, 208A2, 208B1, and208B2; diodes 210A and 210B; two ferrite halves 212A and 212B; battery16; stimulating capacitor 15; molecular sieve moisture getter material235; and unwound conductive coil wire 216. After the final assemblyprocess, the components 200 are encapsulated within, for instance, ahermetically-sealed housing which consists of two cylindrical shellhousings, e.g., a titanium housing 213 and a ceramic housing 215 (bothshown in FIG. 20B). Other suitable housing material(s) and shapes may beused.

The BPB assembly process consists of a series of assembly operationsthat, herein, are grouped into three stages. The first stage comprisesoperations for putting together sub-assembly 200A (shown in FIG. 14A)and further operations to create sub-assembly 200B (shown in FIG. 15A)from sub-assembly 200A and other components; the second stage comprisescreating sub-assembly 200C (shown in FIG. 19) from sub-assembly 200B andother components; and the third stage comprises a process in which thesub-assembly 200C is encapsulated within the exemplaryhermetically-sealed cylindrical housing (shown in FIG. 20A). Materialsused for the manufacturing/assembly process are only exemplary and othersuitable materials may be used.

With reference to FIGS. 8-16 and 21, the first assembly stage will bedescribed. Ten or more units may be assembled together for batchprocessing as illustrated in FIG. 9 in which the substrate panels (202A,202B, 202C, . . . herein also collectively referred to as 202 n) areshown as part of panel assembly 202. By using a batch process, startingwith the substrate panel assembly 202, the assembly procedure andtesting is more efficient as opposed to assembling each unitindividually. The substrate panel assembly 202 is a single layer,double-sided circuit board made of ceramic, organic, or other suitableflexible material(s). The contour of each panel 202 n of the substratepanel assembly 202 may be precut and only small portions of the edgesmay be left attached to the substrate panel assembly 202. The smallportions that are left intact make the alignment of other components andfuture singularization of each panel 202 n much easier, especially whenall other parts have been assembled to the substrate panel assembly 202.

As an initial assembly step, the top surface 204 of substrate panelassembly 202 is used to mount other components, such as the integratedcircuit 206, which is similar in shape to each of the substrate panels202 n. The top surface 204 of the substrate panel assembly 202 isidentified by a printed part number made during the manufacturing of thesubstrate panel assembly 202. Each panel 202 n of substrate panelassembly 202 is uniquely serialized using a laser beam. The serialnumbers are engraved on the bottom surface 205 of the substrate panelassembly 202, and metal pads 203A and 203B (shown in FIGS. 14C, 14D, and15C) carry the serial number, which metal pads are used for test probingduring several steps of the assembly process. Two ferrite half cylinders212A and 212B “sandwich” a separated panel 202 n and associatedintegrated circuit 206. This “sandwich” design maximizes the size of thehalf cylinders 212A and 212B and the coil 18 which receive the powertransfer from the external coil, thus, maximizing the magneticinductance.

The integrated circuit (IC) 206 is a custom designed IC chip. The ICwafer, which includes a multitude of these custom ICs 206, is made usingstandard IC manufacturing processes. The IC wafer is then taken througha post-process called redistribution: A layer of polyimide (or othersuitable insulation) is deposited on the IC surface. Photosensitivematerial is deposited and exposed, e.g., through a mask, in onlyselected areas, as in photochemical etching processes known in the art.The photosensitive material and portions of the polyimide are removed,for instance, to expose the aluminum pads on the surface of the IC. Alayer of titanium tungsten in applied in a similar manner (i.e., usingphotosensitive etching or the like) to the aluminum. A layer of copperis then deposited, and photochemical etching or the like used to removethe areas of copper that are not needed. This layer of copper (aided bythe surrounding layers) creates the “redistribution” of mounting padsand traces that allows secondary components such as diodes 210A and 210Band capacitors 208A1 and 208A2 to be assembled above and bonded to theIC 206 and allows simplified interconnections between the IC 206 and thesubstrate 202 n, as shown in FIG. 13. Again using photochemical etchingor the like, titanium tungsten or other suitable bonding material isapplied to select portions of the copper, where gold or other suitableconductive material will be applied. Another layer of polyimide orsimilar insulation is applied (via photochemical etching or the like) toselect areas. A layer of gold or other conductive material is applied(again, via photochemical etching or the like) to the bonding materialthat was earlier applied to the copper. These added layers on the ICsurface 207 also provide a damping media for protection against thestresses and damages caused by assembly handling and componentplacement.

Using the top surface 204 of the substrate assembly 202 or eachsubstrate panel 202 n, a non-conductive epoxy is applied to attach eachintegrated circuit 206 as shown in FIG. 10. After the ICs 206 areassembled to substrates panels 202 n, each non-serialized IC 206 is nowuniquely identified by the serial number laser engraved on the backsideof substrate panels 202 n, and can be tested and calibrated withcalibration information saved together with the serial number.

Conductive epoxy is applied to portions of the top surface 207 of eachIC 206 to mount, e.g., ceramic, capacitors 208A1 and 208A2, and thediodes 210A and 210B to their respective redistributed interconnectionpads, as shown in FIG. 13. Non-conductive epoxy is applied to a portionof surface 207 of the ICs 206 to attach the top ferrite half 212A, asshown in FIG. 12. Electrical wires 214 are bonded, connecting traces onpanel 202 n to diodes 210A and 210B, and connecting traces on panel 202n to IC 206. An enlarged detail view of the bonded wires 214 is shown inFIG. 13. Quality inspection can be done after this step, as well asother steps in the manufacturing process.

To protect the electrical wires 214 from any damage that may occurduring the assembly process and handling, they may be encapsulated withan epoxy joint 217, as shown in FIG. 14A. The mounting of the componentson the top surface of the substrate panel 202 is now complete.

The bottom half components of the “sandwich” ferrite arrangement areassembled next to the bottom surface 205 of the substrate panel 202 n(as shown in FIG. 14B). A non-conductive epoxy is applied to the portionof the bottom surface 205 used to attach the bottom ferrite half 212B. Aconductive epoxy is then applied to the portion of the bottom surface205 of the substrate panel 202 n used to attach the ceramic capacitors208B1 and 208B2.

The assembled units 200A are separated from panel assembly 202 bybreaking away the pre-cut small portions made to contour the edge ofeach substrate panel 202 n. FIG. 14A shows an isometric top view of asingle sub-assembly 200A showing the wire bonds and diodes encapsulatedin epoxy joint 217. FIG. 14B shows an isometric bottom view of thesub-assembly 200A. FIG. 14C shows the top plan view of the sub-assembly200A showing the two pads 203A and 203B protruding from one end of theferrite “sandwich” arrangement. The pads 203A and 203B can be used fortesting the assembled electrical connections. The pads 203A and 203B arealso used to connect the, e.g., tantalum, stimulating capacitor 15. FIG.14D shows the bottom plan view of the sub-assembly 200A where the twopads 203A and 203B, as well as pads 201A, 201B, 201C, and 201D are alsoused for electrical test probing. The two metal pads 203C and 203D alsocarry the serial number. The bottom of the sub-assembly 200A isidentified by the mark 221 located on the ceramic capacitor 208B 1 toaid in orientation and handling during manufacturing.

The unwound coil wire 216, made of 46 gauge insulated magnetic copperwire or other suitable conductive wire material, is then wound on themiddle section of the ferrite cylinder, as shown in FIG. 15A. The coilwire 216 in a wound configuration is referred to as the BPB coil 18, asshown in FIGS. 1, 15A, and 15B. In this particular assembly process, thecoil 18 has 156 turns and is wound in two layers identified as coillayer 223A and coil layer 223B, as shown in FIG. 15B, which depicts across-section of the sub-assembly 200B (which is the designation givento sub-assembly 200A after it has proceeded through the coil windingprocess). One coil layer or more than two coil layers may also be used.The required amount of layers depends on the frequency, current, andvoltage requirements. Distance A (shown in FIG. 15B) is determined bythe required number of coil turns and distance B (also shown in FIG.15B) is the amount of chamfer depth required to fit the number oflayers. For this application, two layers are shown in FIG. 15B.Minimizing the coil layers, which minimizes the diameter of the coil,allows subassembly 200B to fit in the smallest shell possible, for whicha ceramic or other suitable material can be used. As shown in FIG. 15B,an exemplary “dumbbell” configuration is formed with the arrangement ofthe two ferrite halves 212A and 212B in which the gap formed by thedistances A and B is used to wind the coil 216.

A soldering fixture 226, shown in FIG. 16, is used to assist interminating the coil ends 228A and 228B to pads 201A and 201B of thepanel 202 n, as shown in FIG. 15C. Soldering the coil ends 228A and 228Bbecomes more practical when the sub-assembly 224 is isolated and securedusing soldering fixture 226 or other similar soldering fixture. Thebottom surface of the panel 202 is facing up using the mark 221 toidentify this surface. The sub-assembly 200B is placed in fixture 226with its bottom side facing up and is held firmly in place by handle226A which is tightened by bolt 226B. FIG. 16 shows the sub-assembly200B securely loaded in soldering fixture 226. The two coil ends, 228Aand 228B, are soldered to the pads 201A and 201B (the ones next to theceramic capacitors 208B1 and 208B2 located on the bottom surface ofpanel 202), as shown in FIG. 15C. This step finalizes the first assemblystage after which sub-assembly 200B is complete.

With reference to FIGS. 17-19 and 21, the second assembly stage will bedescribed. A carrier 230, shown in FIG. 17, has been designed tofacilitate the second assembly stage and aid in alignment of components.The carrier 230 consists of two plates, top plate 230A and bottom plate230B. When plates 230A and 230B are bolted together, the machinedfeatures, 231A, 231B, and 231C securely hold the components assembled inthe first operation described above. The top plate 230A also containsopenings 232A, 232B, and 232C to allow access to the assembledcomponents for processing, testing, and inspection. Two bolts 234A and234B, aligned with holes 233A and 233B, are required to fasten plates230A and 230B securely. Holes 233C and 233D are used to secure theassembled carrier 230 on a metal work plate 239 using pins 237A and 237B(shown in FIG. 18). Having the carrier 230 secured on the work plate 239facilitates in a smooth assembly process.

The sub-assembly 200B and the stimulating capacitor 15 are placed in thecarrier bottom plate 230B as shown in FIG. 18, then top plate 230A isbolted to bottom plate 230B with bolts 234A and 234B. Through grooveopening 232B on top plate 230A, conductive epoxy 229 is applied to bondthe gold-coated nickel ribbon attached to one end of the capacitor 15 tobond to pads 203A and/or 203B (seen best in FIGS. 14C and 14D). At thispoint, while in the carrier 230, the assembly is tested (as it isthroughout the manufacturing process) and is also processed throughbaking temperature cycling.

The top carrier plate 230A is removed, the battery 16 is securely placedin the carrier groove 231C of bottom plate 230B, then top plate 230A isbolted back in place. The battery 16 has two nickel wires 68A and 68B(shown in FIG. 5) which have been pre-welded. Battery 16 is placed intogroove 231C so the nickel wires 68A and 68B protrude towards the bottomsurface 205 of the substrate panel 202 n. Using groove opening 232B,where the nickel wires 68A and 68B of the battery 16 and the assembly200B come together, an amount of non-conductive epoxy 219 is applied sothat the ends of wires 68A and 68B are still accessible. The nickelwires 68A and 68B are bent towards and soldered to the substrate pads201C and 201D. Additional non-conductive epoxy 219 is applied to securethe connection between the soldered nickel wires 68A and 68B and pads201C and 201D. This finalizes the second assembly stage when thesub-assembly 200C as shown in FIG. 19 is complete.

With reference to FIGS. 20A, 20B, 20C, and 21 the third assembly stagewill be described. The assembly 200C is encapsulated within an exemplaryhermetically-sealed housing which consists of, for instance, twocylindrical cases, a titanium 6/4 case 213 and a zirconia ceramic case215, as best seen in the cross sectional view FIG. 20B. Alternativematerials and shapes for the housing may also be used. A titanium 6/4 orother suitable connector 236 is brazed with a titanium nickel alloy (orother suitable material) to the ceramic case 215 for securing the matingend of the titanium case 213. The connector 236 has an inside flange236A and an outside flange 236B which serve to “self center” the brazeassembly. Before inserting the subassembly 200C and before securing themating ends, conductive silicone adhesive 238 is applied to the insideend of the ceramic shell as well as to the inside end of the titaniumshell. A molecular sieve moisture getter material 235 is also added toareas 235A, 235B, and 235C as shown in FIG. 20B before the brazingprocess.

The “spiral” self-centering button electrode 22 is made from titanium6/4 or other suitable material and is plated with an iridium coating orother suitable conductive coating. An end view of electrode 22 is shownin FIG. 20C. A spiral groove 324 is made to stimulating surface 322 ofthe electrode 22. The spiral groove 324 is just one example of grooveshapes that may be used; other shapes, such as a cross hatch pattern orother pattern may also/instead be used. Groove 324 increases theconductive surface area 322 of electrode 22.

The sharp edges in groove 324 force a more homogeneous currentdistribution over the surface 322 and decrease the chances of electrodecorrosion over time. The corrosion effect, which may affect theelectrode 22, is also known as biofouling, which is the gradualaccumulation of bacteria on the surface of the electrode 22 onceimmersed in body fluid. When current is injected into body fluids, anelectro chemical reaction occurs, producing large amounts of currentdensity, which can contribute to the accumulation of bacteria. Thespiral groove 324 or similar groove helps reduce the current densityalong the sharp groove edges. A tool made in the shape of a trapezoid orsimilar shape is used to cut the groove 324 into a spiral or othershape. Other methods of cutting the groove 324 may be used, e.g., ionbeam etching.

The button electrode 22 becomes the active or stimulating electrode. Atitanium/nickel alloy 240 or other suitable material is used to brazethe button electrode 22 to the zirconia ceramic case 215. An end view ofthe BPB device 10 is shown in FIG. 20C where the end view of thestimulating “spiral” button electrode 22 can be seen. The end 242 of thetitanium shell 213 is plated with an iridium coating (other suitableconductive coating may be applied), which plated area becomes theindifferent iridium electrode 24, as shown in FIG. 20A.

FIG. 20A shows a top view of the assembled BPB device 10 with theexternal coatings depicted. A type C parylene or other suitableinsulation coating is applied to the shaded area 244, e.g., by standardmasking and vapor deposition processes. The zirconia ceramic case isleft exposed in area 248 and the iridium electrode 24 is shown on theend 242 of the titanium case 213. This step completes the assemblyprocess of the BPB device 10. A cross-section of the final assembled BPBdevice 10 is shown in FIG. 20B.

U.S. Pat. No. 6,582,441, incorporated herein by reference, describes asurgical insertion tool that may be used for implanting the BPB devicetaught in this invention. The procedures taught in the '441 patent forusing the tool and associated components may be used for implanting andextracting the BPB device 10 taught in the present invention. Thesurgical insertion tool described in the '441 patent facilitates theimplantation of the BPB device in a patient such that the stimulatingelectrode 22 is in very close proximity to the stimulating nerve site(e.g., near the pudendal nerve for treating patients with urinary urgeincontinence). The proximity range may be, for example, less than 1-2mm.

Other implantation procedures exist relating to the specific area to bestimulated. The implantable BPB device 10 may also be implanted in othernerve sites relating to preventing and/or treating various disordersassociated with, e.g., prolonged inactivity, confinement orimmobilization of one or more muscles and/or as therapy for variouspurposes including paralyzed muscles and limbs, by providing stimulationof the cavernous nerve(s) for an effective therapy for erectile or othersexual dysfunctions, and/or by treating other disorders, e.g.,neurological disorders caused by injury or stroke.

When the power source used within the BPB device is something other thana rechargeable battery, e.g., a primary battery and/or one of thealternative power sources described previously, then the circuitrywithin the electronic subassembly 14 (FIG. 1) is modified appropriatelyto interface with, control, and/or monitor the particular power sourcethat is used. For example, when the power source comprises a primarybattery, the circuitry within the electronic subassembly may besimplified to include only monitoring circuitry, not charging circuitry.Such monitoring circuitry may provide status information regarding howmuch energy remains stored within the primary battery, thereby providingthe physician and/or patient an indication relative to the remaininglife of the battery.

When the power source used within the BPB device is a super capacitor,then such super capacitor will typically be used in combination with aprimary battery and/or a rechargeable battery. When used in combinationwith a primary battery, for example, the circuitry within the electronicsubassembly is modified appropriately so that the charge stored on thesuper capacitor is available to help power the BPB device during timesof peak power demand, such as during those times when telemetry signalsare being transmitted from the implanted device to the externaldevice(s), or when the amplitude of the stimulation pulses has beenprogrammed to be very high. When used in combination with a rechargeablebattery, the circuitry within the electronic subassembly is modifiedappropriately so that the charge stored on the super capacitor isavailable to help recharge the rechargeable battery or to help power theBPB device at times of high power demand.

While the invention herein disclosed has been described by means ofspecific embodiments and applications thereof, numerous modificationsand variations could be made thereto by those skilled in the art withoutdeparting from the scope of the invention set forth in the claims.

The invention claimed is:
 1. A method for controlling an implantable medical device, the device having telemetry circuitry to receive both a first type of telemetry and to receive a second type of telemetry, the method comprising: listening for the first and second telemetry types; monitoring a voltage of a power source within the implantable medical device; and if the voltage falls below a first threshold, discontinuing listening for the first telemetry type while continuing listening for the second telemetry type.
 2. The method of claim 1, wherein the first telemetry type comprises Frequency Shift Keying (FSK), and wherein the second telemetry type comprises On/Off Keying (OOK).
 3. The method of claim 2, wherein the telemetry circuitry comprises an OOK receiver, an FSK receiver, and an FSK transmitter.
 4. The method of claim 1, wherein the first threshold is stored in a first register in the implantable medical device.
 5. The method of claim 1, further comprising if the voltage later exceeds the first threshold after falling below the first threshold, resuming listening for the first telemetry type.
 6. The method of claim 1, further comprising if the voltage falls below a second threshold lower than the first threshold, detecting a charging field and continuing to listen for the second telemetry type.
 7. The method of claim 1, further comprising if the voltage falls below a second threshold lower than the first threshold, disabling circuitry in the implantable medical device except circuitry required for recharging the battery.
 8. The method of claim 7, further comprising receiving programming and recharging by a clinician.
 9. The method of claim 1, wherein the power source comprises a lithium ion battery.
 10. The method of claim 1, wherein the implantable medical device is configured to provide electrical stimulation to a patient, and further comprising enabling stimulation while listening for the first telemetry type, and disabling stimulation if the voltage falls below the first threshold. 